U3V70F9 how to protect against LC voltage spikes?


I have 2 questions about the 9V Step-Up Voltage Regulator U3V70F9:

  1. There is no mention on the product page (https://www.pololu.com/product/2894) about how to protect against LC voltage spikes? On some other voltage regulator product pages, for example, the Pololu 9V Step-Up Voltage Regulator U3V12F9 (https://www.pololu.com/product/2116), i’ve seen the decoupling capacitor values are mentioned, but not for this product? Why? Does the U3V70F9 not require a decoupling capacitor?

  2. Also, why choose the 9V Step-Up Voltage Regulator U3V70F9 over the 9V Step-Up Voltage Regulator U3V12F9? In what applications would one be preferred over the other?

Thanks in advance for the help.


We do not expect LC spikes to damage the U3V70F9 regulator, but if your input voltage spikes above 9V the spike will also be seen on the output. If that is a concern, you could add some capacitance across VIN and GND to help protect devices connected to the regulator’s output.

The U3V70F9 regulator can source a lot more current than the U3V12F9, so for higher current applications it is clearly a better choice.


Thank you for the response. I am using an 8.4 V DC battery as input to the U3V70F9 regulator. To protect against LC voltage spikes, what decoupling capacitor ratings do you suggest/recommend? I think a 35 V capacitor should be safe but what about its capacitance value?

To be really safe, I suggest doubling your 8.4V, so a 16-25V 33 μF or larger electrolytic capacitor should be fine (35V should be fine too).